You should start thinking about that.

Many point-of-sale machines now are essentially just a smartphone with a card reader attached and the interface. The control layout can change at a moment's notice and there are no physical boundaries between buttons. With a keypad-style machine, the buttons are always in the same place and can be located by touch, especially since the middle button has a raised ridge on it.

Buttons can also be located by touch without activating them, which enables a "locate then press" style of interaction which is not possible on touchscreens, where even light touches will register as presses and the buttons must be located visually rather than by touch.

When elevator or door controls are replaced by touch screens, will existing accessibility features be preserved, or will some people no longer be able to use those controls?